Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.


  1. Advanced Patent Search
Publication numberUS2602134 A
Publication typeGrant
Publication dateJul 1, 1952
Filing dateOct 3, 1947
Priority dateOct 3, 1947
Publication numberUS 2602134 A, US 2602134A, US-A-2602134, US2602134 A, US2602134A
InventorsNelson Richard Burton
Original AssigneeGen Electric
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
High-frequency dielectric heater
US 2602134 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

y 1952 R. B. NELSON HIGH-FREQUENCY DIELECTRIC HEATER Filed Oct. 5, 1947 Inventor:

n o m e N B d r a h m R by Hus Attorney.


Richard Burton Nelson, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application October 3, 1947, Serial No. 777,834

2 Claims.

My invention relates to high frequency dielectric heaters utilizing electromagnetic fields, and has for its object a simple and reliable heater of this type for continuously'heating granular dielectric materials, more particularly for popping corn.

In carryingout my invention in one form, I utilize a funnel-shaped member made of low loss dielectric. material into which the popcorn is fed and forced upward by a blast of air, together with high frequency dielectric heating means for heatin the kernels of corn while suspended in the air blast which carries the lighter popped corn out of the upper end of the funnel-shaped member.

For a more complete understanding of my invention, reference should be had to the accompanying drawing, Fig. l of which is a view in section of a high frequency heater for popping corn embodying my invention, while Fig. 2 is a fragmentary view in section of a modified form of my invention.

Referring to the drawing, in one form of my invention I provide a quartz tube I which is mounted in a substantially vertical position and the upper end of which is enlarged to form a funnel-shaped portion 2. The popcorn 3 is fed into the tube I through a feed tube 4 adjacent its lower end and is carried upward through the tube into the funnel portion by a compressed fluid, preferably a gas such as air, supplied to the lower end of the tube I from a suitable source, such as a pressure tank or air compressor. The portion 5 of the feed tube is bent upward at its junction with the tube I so that a slight vacuum is formed in the portion 5 by the stream of air moving upward, whereby the kernels of corn are drawn into the tube I.

The air pressure, and therefore the velocity of the stream of air moving upward, is adjusted so that the air stream carries the grains of corn upward through the tube I into the funnel-shaped portion 2 where the air stream expands and its velocity decreases. The kernels of corn continue to move upward into the funnel 2 to a location where the reduced air velocity is just sufficient to support or suspend the grains, as indicated by the reference numeral 6, and the grains remain in that position while they are being heated.

For the purpose of heating the grains of corn in the funnel 2, I provide suitable high frequency dielectric heating means, shown as a heating chamber, formed by top, bottom, and side walls I, 8, and 9, made of electrically conducting material, such as copper. As shown, the side wall 9 may be cylindrical. The top and bottom walls are provided with central apertures for the funnel 2 which extends through the chamber. By means of suitable coupling means, shown as a loop I0, connected to a suitable source of high frequency current supply, not shown, electromagnetic fields having a desired mode are produced in the chamber whereby standing electromagnetic waves are produced in thechamber; These fields freely penetrate the quartz wall of the funnel 2 and, likewise, the grains of corn in the heating zone, whereby the; corn is heated. But little, if any, heat is generated in the quartz wall of the funnel because of the'comparatively low power factor of the quartz material. Moreover, current is supplied to the loo in from the supply source at a high frequency suitable for the effective heating of the corn, or other dielectric material having a relatively high 1055 characteristic Without substantial heating of the funnel, such as 2000 megacycles.

As shown, the walls of the heating chamber surround the funnel throughout substantially its entire length and, preferably, the electromagnetic fields in the chamber are positioned so as to start the heating of the corn immediately after it passes into the chamber. This heating continues as the corn moves upward into the funnel. and I contemplate that when the corn reaches the position 6 of substantially stable equilibrium in the air stream the corn will be heated substantially, or nearly, to the popping temperature. When the corn pops, the kernel, of course, enlarges with greatly decreased density, 1. e., low specific gravity, and, consequently, the popped kernels II are immediately blown out of the top of the funnel by the air stream.

I contemplate, also, that a plate or electrode type of dielectric high frequency heater may be utilized instead of the chamber. Such an arrangement is shown in Fig. 2, in which two plate electrodes I2 and I3 are provided on opposite sides of the funnel 2. These electrodes are connected to a suitable source of high frequency supply having a much lower frequency than required with the form shown in Fig. 1, such as megacycles.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A high frequency dielectric heater for heating a granular material which expands and whose specific gravity decreases with an increase in temperature, comprising a funnel-shaped member of relatively low power factor dielectric material mounted in an upright position with the larger end upward, said upper end being open, means for supplying a gas under a predetermined pressure to the lower end of said member for producing an upwardly directed gas current in said member having a velocity sufiicient to support the granular material to be heated in a predetermined position of equilibrium within said member, tube means communicating with the lower portion of said member for feeding the granular material to be heated into said member whereby said material is blown upward by said gas current to said predetermined position, and electrically conductive mean positioned externally of said member for producing within said member including said predetermined position a high frequency field to heat said material whereby to increase its volume and decrease its specific gravity sufliciently to cause said material to be carried upward by the gas current and out of said upper end of said member.

2. A high frequency dielectric heater for heating pop corn and the like comprising a funnelshaped member of relatively low power factor dielectric material mounted in an upright position with the larger end upward, said upper end being open, means'for supplying air under a predetermined pressure to the lower end of said member for producing an upwardly directed air current in said member having a velocity sufficient to raise the pop corn kernels from the lower portion of said member to a predetermined location of equilibrium defining a heating zone within said member where the reduced air velocity due to in creased cross-section of the funnel member is just sufiicient to suspend said kernels in said air current, tube means communicating with the lower portion of said member for feeding said kernels into said member, said kernels being drawn into said member by the vacuum created in said tube by the upward. air current and being blown upward by said air current to said heating zone, a heating chamber of electrically conductive material surrounding a. portion of said member including said heating zone, said chamber being provided with apertures in the top and bottom through which said member extends through said chamber, and means for producing within said chamber including the portion of said member surrounded thereby high frequency standing electromagnetic waves to heat said kernels and cause them to pop, said kernels being carried upward after popping by said air current and out of said upper end of said member.


REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 21,653 Bigelow Dec. 10, 1940 1,888,372 Bramwell Nov. 22, 1932 1,972,050 Davis Aug. 28, 1934 2,054,441 Peebles Sept. 15, 1936 2,125,207 Suggs July 26, 1938 2,132,961 Morgan Oct. 11, 1938 2,364,526 Hansell Dec. 5, 1944 2,413,420 Stephanofi Dec. 31, 1946 2,473,539 Merriam June 21, 1949 2,480,679 Spencer Aug. 30, 1949 2,497,501 Himmel et al Feb. 14, 1950 2,500,752 Hanson et a1. Mar. 14, 1950 OTHER REFERENCES Engineering Abstracts, Product Engineering, January 1947, pages 137-140, particularly pages 138 and 139.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1888372 *Feb 13, 1930Nov 22, 1932Birtley Iron Company LtdSeparation of dry materials
US1972050 *Aug 8, 1932Aug 28, 1934Jesse H DavisHigh frequency method of and apparatus for exterminating insect life in seed or grain or other materials
US2054441 *Jan 29, 1932Sep 15, 1936Western Condensing CoMethod and apparatus for drying liquid containing materials
US2125207 *Nov 9, 1936Jul 26, 1938Suggs Hilbert EVacuum peanut stoner
US2132961 *Sep 5, 1936Oct 11, 1938Jabez Burns & Sons IncCleaner for coffee and other grains
US2364526 *Jul 10, 1941Dec 5, 1944Rca CorpHigh frequency induction system
US2413420 *Feb 26, 1940Dec 31, 1946Thermo Plastics CorpMethod and apparatus for dispersing or drying fluent material in high velocity elastic fluid jets
US2473539 *Nov 2, 1944Jun 21, 1949Guardite CorpHigh-frequency drying
US2480679 *Mar 29, 1947Aug 30, 1949Raytheon Mfg CoPrepared food article and method of preparing
US2497501 *Apr 27, 1946Feb 14, 1950Ross M CarrellTreatment of coffee, etc.
US2500752 *Jun 1, 1946Mar 14, 1950Gen ElectricHigh-frequency dielectric heating in a resonant chamber
USRE21653 *Sep 7, 1935Dec 10, 1940 Device foe dry separation of pke-
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2859116 *Jun 7, 1954Nov 4, 1958Heimbs & SohnTreatment of coffee and other materials
US2888542 *Sep 28, 1955May 26, 1959Raytheon Mfg CoHeating apparatus
US2922355 *Feb 25, 1958Jan 26, 1960Gen Foods CorpCorn popping apparatus
US2939379 *Feb 25, 1959Jun 7, 1960Schmitt Roland GApparatus for popping popcorn
US2992921 *Jan 12, 1959Jul 18, 1961M J BProcessing of brown rice
US3133484 *Sep 29, 1961May 19, 1964Rca CorpElectrostatic printing apparatus
US3261959 *Feb 20, 1962Jul 19, 1966F H Peavey & CompanyApparatus for treatment of ore
US3323440 *Oct 7, 1964Jun 6, 1967Grant Don SCorn popping apparatus
US3366497 *Feb 9, 1965Jan 30, 1968Pet IncMethod of producing a low viscosity, high density fruit juice concentrate
US3440731 *Feb 8, 1966Apr 29, 1969Atomic Energy CommissionMagnetically stabilized fluidized bed
US3668358 *May 21, 1970Jun 6, 1972Alfa Laval AbApparatus for electromagnetic heating of liquids
US3756139 *Apr 12, 1972Sep 4, 1973Wolens JPopcorn popper
US4152974 *Jun 16, 1978May 8, 1979National Presto Industries, Inc.Hot air corn popper
US4156806 *Dec 30, 1977May 29, 1979Raytheon CompanyConcentrated energy microwave appliance
US4157061 *May 5, 1977Jun 5, 1979Continental Seafoods, Inc.Process and apparatus for cooking
US4178843 *Feb 6, 1978Dec 18, 1979Wear-Ever Aluminum, Inc.Portable corn popper
US4292344 *Feb 23, 1979Sep 29, 1981Union Carbide CorporationFluidized bed heating process and apparatus
US4477705 *Jun 1, 1982Oct 16, 1984Plastics, Inc.Microwave oven popcorn popper, steamer and roaster
US4873406 *Dec 23, 1988Oct 10, 1989Connor Gary LMicrowave popcorn popper
US4947740 *Feb 16, 1990Aug 14, 1990Strawser Michael GPopcorn popper
US4958054 *Oct 29, 1986Sep 18, 1990Fritto-Lay Inc.Dielectric drying of hot plastic food extrudate
US4980530 *May 31, 1989Dec 25, 1990I. K. International B. V.Dielectric high frequency fryer
US5247148 *Jun 1, 1992Sep 21, 1993Alexander MencherMicrowave fluid heater with capacitive plates
US5357088 *May 4, 1992Oct 18, 1994Konica CorporationMethod for melting a photographic composition gel to a sol using microwave energy
US5397879 *Nov 17, 1993Mar 14, 1995National Presto Industries, Inc.Microwave corn popper device and method
US5695673 *Feb 23, 1995Dec 9, 1997National Presto Industries, Inc.Microwave cooking device including susceptor retainer and method
US5798137 *Jun 7, 1995Aug 25, 1998Advanced Silicon Materials, Inc.Method for silicon deposition
US5810934 *Jun 7, 1995Sep 22, 1998Advanced Silicon Materials, Inc.Silicon deposition reactor apparatus
US5977532 *Mar 6, 1995Nov 2, 1999Antrad System AbMethod and apparatus for using electromagnetic radiation to heat a dielectric material
US6299922 *Oct 19, 1999Oct 9, 2001Rudolf BichselDevice and method for puffing granular material
US6350973 *Jul 24, 1997Feb 26, 2002Ea Technology LimitedRadio-frequency and microwave-assisted processing of materials
US8993946Mar 11, 2013Mar 31, 2015Sterling, LLCSingle-mode microwave popping device
US20140255569 *Mar 11, 2013Sep 11, 2014Sterling L.C.Methods for popping kernels to achieve improved popping yield
WO2014164527A3 *Mar 10, 2014Dec 31, 2014Sterling, LcMicrowave popping device and method
U.S. Classification219/762, 159/DIG.260, 99/DIG.140, 219/693, 34/255, 219/725, 99/323.5, 99/516, 426/244
International ClassificationH05B6/78, A23L1/18, A23P1/14
Cooperative ClassificationH05B6/78, A23L1/1812, Y10S99/14, Y10S159/26, A23P1/148
European ClassificationA23P1/14D, H05B6/78, A23L1/18C6